Ultra-Narrow Metallic Nano-Trenches Realized by Wet Etching and Critical Point Drying.

Area of Science:

• Nanophotonics and Plasmonics
• Materials Science
• Surface Chemistry

Background:

• Metallic nano-trenches are crucial optical structures for molecular detection and electrochemical applications.
• Existing wet-etching methods for metal-insulator-metal structures create nano-trenches but are limited by gap collapse during drying.

Purpose of the Study:

• To overcome the limitations of current fabrication methods and achieve metallic nano-trenches with sub-5 nm gap widths.
• To enable new optical and electrochemical studies at the few-molecules-thick level.

Main Methods:

• Utilized critical point drying to mitigate surface tension-induced collapse during the fabrication of metallic nano-trenches.
• Employed wet-etching of dielectrics in metal-insulator-metal structures to create the nano-trenches.
• Characterized the fabricated nano-trenches using Terahertz spectroscopy.

Main Results:

• Successfully fabricated metallic nano-trenches with gap widths as small as 1.5 nm, overcoming the previous 5 nm limit.
• Terahertz spectroscopy confirmed successful dielectric etching and the integrity of the ultra-narrow gaps.
• Demonstrated a method to prevent nano-trench collapse during the drying process.

Conclusions:

• Critical point drying is an effective technique for fabricating stable, ultra-narrow metallic nano-trenches.
• This advancement opens possibilities for high-sensitivity molecular sensing and advanced electrochemical studies.
• The developed method is expected to facilitate research on nanoconfined molecules and few-molecule-thick systems.